The purpose of the proposed study is to determine the extent to which electrical potentials can influence osteogenic activity in porous coated implant materials. The growth of tissue into porous implants has been well established as a feasible means of attaching load-bearing prosthesis to the musculo-skeletal system. Attachment by in growth eliminates most of the problems associated with other means of fixation, but has itself the disadvantage that the patient must be immobilized for long periods of time to permit sufficient ingrowth to ensure stability. The stimulation of bone by imposed electrical potentials has been demonstrated for fracture healing and for some 'preliminary' bone growth into porous coated implants. The proposed study is directed to broaden our knowledge of the effect of electrical stimulation on: (1) the actual interfacial strength of implant/tissue union; (2) the kinetics of tissue ingrowth and (3) the morphology of the union. Carefully sectioned push-out specimens will be made to test the strength of the unions and comparisons will be made between the electrically stimulated and non-stimulated control samples along the length of the femur. The kinetics of tissue ingrowth will be determined quantitatively by a conmbination of wet chemical assaying and microscopic techniques. A porous polymer (polymethylmethacrylate) and metal (Co-Cr-Mo alloy) that are sintered to a solid metal core approximately 2 mm thick will be implanted in the intramedullary cavity of canine femurs since these materials are being investigated for their usefulness as porous implant materials in orthodpedic and dental application by the principal investigator.